R37AI116313

Multifaceted interactions between lentiviral VIF and host molecules for viral infectivity enhancement - Project description

The APOBEC3 (A3) family of proteins are cellular cytidine deaminases that suppress human immunodeficiency virus type 1 (HIV-1) infection by hypermutation of viral reverse transcripts and physically blocking reverse transcription. To evade this host defense mechanism, HIV-1 expresses the virion infectivity factor (VIF), which hijacks a cellular E3 ubiquitin ligase complex and targets A3 proteins (A3F/G/H/D) for proteasome-mediated degradation.

Besides degrading A3s, HIV-1 VIF also causes G2 cell cycle arrest by targeting multiple protein phosphatase 2A (PP2A) regulators (PPP2R5 proteins) for degradation. Adding to the complexity of VIF-host protein interactions, HIV-1 VIF utilizes the transcription factor CBFSS as a non-canonical cofactor, while Maedi-Visna virus (MVV) VIF co-opts the prolyl isomerase cyclophilin A (CYPA) instead.

Our goal is to establish the biochemical and structural principles for the multifaceted activities of lentiviral VIF molecules that recruit cellular factors to degrade host proteins via ubiquitin-proteasome pathways. To achieve our goal, we will use a combination of biochemical, biophysical, structural biology, and cellular functional techniques.

To establish the mechanisms by which A3 proteins are targeted by the HIV-1 VIF (Aim1), we will determine high-resolution structures of the A3-VIF-E3 interaction complexes, validate these structures by structure-guided mutagenesis experiments in vitro and in vivo, and interrogate the molecular determinants of VIF/A3/E3 ligase assembly and activation. In addition, we will also study the degradation-independent mode of VIF inhibition of A3 deamination and antiviral activities.

To better understand CYPA-mediated formation of MVV VIF-E3 ubiquitin ligase (Aim2), we will assemble MVV VIF/CYPA/E3 ligase complexes with or without A3 substrates, determine their high-resolution structures, and perform biochemical and functional validations of our structural observations. The influences of capsid proteins on the assembly and activation of MVV VIF-E3 ligase will also be investigated.

To delineate the mechanisms of PPP2R5/PP2A recruitment by lentiviral VIF-E3 ubiquitin ligases (Aim3), we will investigate the effects of PPP2R5 proteins on the assemblies of the CBFSS-mediated HIV-1 VIF and CYPA-mediated MVV VIF-E3 ligases, obtain high-resolution structures, and perform structure-guided validations.

Our comprehensive research design provides a robust approach that will generate unprecedented insights into the diverse functions of lentiviral VIF molecules.

Yale Univ

NOT APPLICABLE

93.855 - Allergy and Infectious Diseases Research

National Institute of Allergy and Infectious Diseases (NIAID) [HHS - NIH]

New Haven, Connecticut 06511 United States

Single Zip Code

NIH Research Project Grant (Parent R01 Clinical Trial Not Allowed) (PA-20-185)

Amendment Since initial award the End Date has been extended from 05/31/26 to 05/31/31 and the total obligations have increased 538% from $502,500 to $3,204,870.